(a) Field of the Invention
The present invention relates to a torque converter in a vehicle, in which a torsional damper reduces a natural frequency and absorbs vibration energy in an anti-resonance state for enhancing a vibration isolation function.
(b) Description of the Related Art
In general, the torque converter is mounted between an engine and a transmission of the vehicle for transmission of driving power from the engine to the transmission by using a fluid. The torque converter is provided with an impeller for receiving driving power from the engine to rotate, a turbine for being rotated by oil being discharged from the impeller, and a reactor (called a ‘stator’) for directing an oil flow returning to the impeller to a rotation direction of the impeller to enhance a torque change rate.
Since power transmission efficiency of the torque converter may become poorer if a load on the engine becomes high, the torque converter has a lock-up clutch (called a ‘damper clutch’) which can directly connect the engine and the transmission. The lock-up clutch is arranged between a front cover directly connected to the engine and the turbine for transmission of the torque directly from the engine to the transmission through the turbine.
The lock-up clutch includes a piston at a turbine shaft, which is movable in an axis direction. The piston has a friction member coupled thereto to be in frictional contact with the front cover. The piston has the torsional damper coupled thereto for absorbing an impact and vibration acting in a rotation direction of the shaft when the friction member is coupled to the front cover.
The torsional damper has springs mounted thereto in a rotation direction for absorbing a torsional torque in a case the lock-up clutch is operated to enable the torsional damper to directly transmit the driving power from the engine to the transmission through the turbine.
That is, a related art torsional damper has a problem in that use of coil springs for the most part arranged in a circumferential direction causes inadequate vibration isolation.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.